Is ultrasound prior to skin incision useful in cesarean (caesarean) deliveries?

Ultrasound Prior to Skin Incision in Cesarean Deliveries

Routine ultrasound prior to skin incision in cesarean deliveries is not recommended as standard practice, but should be considered in specific high-risk scenarios such as suspected placenta accreta spectrum disorder or difficult fetal presentation.

Indications for Pre-Incision Ultrasound

Ultrasound prior to cesarean section skin incision may be beneficial in the following situations:

High-Value Clinical Scenarios

• Suspected placenta accreta spectrum disorder (PASD)

  • Particularly in women with risk factors such as:
    • Prior cesarean deliveries
    • Placenta previa
    • Prior uterine surgery
  • MRI may complement ultrasound in complex cases but is not the preferred initial modality 1

• Uncertain fetal presentation or position

  • To confirm non-cephalic presentations
  • To determine optimal incision location for difficult presentations

• Suspected low-lying anterior placenta

  • To guide incision placement and avoid placental injury

Limited Value in Routine Cases

• For standard cesarean deliveries without risk factors, routine pre-incision ultrasound has not been shown to significantly impact maternal or fetal outcomes 2
• A 1988 study found that "routine visualization of the intrauterine contents before surgery is not necessary" though "worthwhile information may be gained in select cases" 2

Evidence-Based Recommendations

Guidelines for Specific Conditions

Placenta Accreta Spectrum Disorder

• Women with suspected PASD should be delivered at a level III or IV center with considerable experience whenever possible 1
• Ultrasound evaluation is important for PASD diagnosis, though absence of ultrasound findings does not preclude diagnosis 1
• For suspected PASD, detailed ultrasound assessment should include:
  • Gray-scale abnormalities (vascular lacunae, loss of hypoechoic zone)
  • Color flow Doppler imaging to detect turbulent lacunar blood flow 1

Skeletal Dysplasia

• In cases of suspected fetal skeletal dysplasia, high-level ultrasound expertise and evaluation is recommended prior to delivery 1
• This helps direct pregnancy management and counseling 1

Technical Considerations

• When ultrasound is indicated, it should be performed by practitioners with appropriate expertise
• For PASD, standardized reporting of ultrasound findings is recommended to improve diagnostic accuracy 1

Practical Implementation

Timing of Pre-Incision Ultrasound

• When indicated, ultrasound should be performed shortly before the cesarean section
• For PASD assessment, detailed evaluation should occur earlier in pregnancy with follow-up as needed

Alternative Applications of Ultrasound in Cesarean Delivery

• Spinal Anesthesia Guidance

  • Ultrasound guidance for spinal anesthesia can be beneficial in patients with difficult-to-palpate anatomic landmarks
  • Reduces number of skin punctures and improves first-attempt success rates 3

• Evaluation of Previous Cesarean Scars

  • 3D ultrasound measurement of previous cesarean scars can help determine mode of delivery in subsequent pregnancies
  • A threshold value of 3.5mm scar thickness has been suggested as a "cut-off value" for considering vaginal birth after cesarean 4

Conclusion

While routine pre-incision ultrasound is not necessary for all cesarean deliveries, it provides valuable information in specific high-risk scenarios, particularly for suspected placenta accreta spectrum disorder, uncertain fetal presentation, or low-lying placenta. The decision to use ultrasound should be based on individual risk factors and clinical indications rather than as a standard protocol for all cesarean deliveries.